A-level Biology (7401/7402)

2 max

(c)     1.      Water used for support / turgidity;

Accept: water used in (the cell’s) hydrolysis or condensation (reactions) for one mark. Allow a named example of these reactions

2.      Water used in photosynthesis;

3.      Water produced in respiration;

4.      Apparatus not sealed / ‘leaks’;

2 max

(d)     As number of leaves are reduced (no mark),

Accept: converse arguments

1.      Less surface area / fewer stomata;

3.      Less evaporation / transpiration;

4.      Less cohesion / tension / pulling (force);

3

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M11.(a)     Prevents oxygen being taken up / entering / being absorbed;

Accept: any idea of no contact with oxygen.

Neutral: for anaerobic respiration / anaerobic conditions.

Neutral: prevents entry of air.

Reject: prevents entry of oxygen and another named gas.

1

(b)     (i)      0.0155 / 0.016 = 2 marks;;

0.0775 / 0.077 / 0.078 / 0.08 = 1 mark

/ 0.62 = 1 mark

2

(ii)     Glucose decreases / is a limiting factor / increase in ethanol / yeast / cells die / toxins build up;

Accept: glucose is used up.

1

(iii)    1.      (Stays the) same / level / (relatively) constant;

2.      Same volume / amount of oxygen uptake and carbon dioxide release;

Note: if m.p.1 is awarded m.p 2 can be obtained without referring to ‘same volume / amount’.

2

(c)     1.      Oxygen is final / terminal (electron) acceptor / oxygen combines with electrons and protons;

2.      Oxidative phosphorylation / electron transport chain provides (most) ATP / only glycolysis occurs without oxygen / no Krebs / no link reaction;

2

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M12.(a)     1.      To show the effect of the inhibitor / drug;

2.      To show the effect of yoghurt (on its own does not affect blood

glucose);

2

(b)     1.      Food is a factor affecting blood glucose / different foods contain

different amounts of starch / glucose / sugar / carbohydrate;

Accept converse

2.      To keep starch / fibre intake the same / similar;

Accept something in food which affects the inhibitor

2

(c)     1.      Fewer E-S complexes formed;

2.      (With inhibitor) less / no starch digested to maltose ;

Require knowledge that maltose comes from starch

3.      (So) less / no glucose from maltose;

Require knowledge that glucose comes from maltose

Accept no glucose

4.      (So) less absorption of glucose (from gut);

2 max

(d)     Suitable reason; with explanation;

Paired responses – do not mix and match

Ignore references to correlation does not prove causation,
it could be due to other factors

Examples,

1.      Need larger sample / only 30 mice / only 15 mice in each group;

Accept small sample size

2.      Might not be representative / anomalies might have a bigger or smaller effect;

Accept mean not reliable

OR

3.      Investigation only lasted 20 days;

Experiment was not long enough

4.      Can’t see what longer term effects are;

OR

5.      Fall in blood glucose is small / numbers from graph;

6.      Mice with inhibitor still have a large rise in blood glucose / so don’t know if differences significant;

Accept differences are due to chance

OR

7.      No stats / SDs / SEs;

8.      So don’t know if differences significant;

OR

9.       Blood glucose could continue to fall;

10.     which could be harmful;

OR

11.     No group without yoghurt;

12.     So cannot compare to other groups;

2 max

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M13.(a)     1.      Equilibrium reached.

Accept equilibrate

2.      Allow for expansion / pressure change in apparatus;

3.      Allow respiration rate of seeds to stabilise.

Ignore seeds acclimatise

3

(b)     1.      Optimum temperature / temperature for normal growth of seeds;

2.      (Optimum temperature) for enzymes involved in respiration.

2

(c)     1.      Oxygen taken up / used by seeds;

2.      CO₂ given out is absorbed by KOH (solution);

3.      Volume / pressure (in B) decreases.

3

(d)     0.975 / 0.98.

If incorrect,

0.26 × 6 / or incorrect numbers divided by 1.6 for 1 mark

2

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